In computing, a pointing device functions by detecting two-dimensional motion relative to its supporting surface. The pointing device sometimes features other elements, such as “wheels”, which allow the user to perform various system-dependent operations, or extra buttons or features can add more control or dimensional input. The motion of the pointing device typically translates into the motion of a pointer on a display, which allows for fine control of a Graphical User interface (GUI). Typically these pointing devices utilize a “point and click” sequence of moving the cursor to the desired position and depressing a button to select an action.
There are several different styles of pointing devices such as a mouse, trackball, joystick, touchpad and the like. A mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons. A mouse may sometimes features other elements, such as “wheels”, which allow the user to perform various system-dependent operations, or extra buttons or features that can add more control or dimensional input.
A trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes-like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a cursor. Large tracker balls are common on graphical workstations for easy precision.
A joystick is an input device consisting of a stick that pivots on abuse and reports its angle or direction to the device it is controlling. Joysticks are often used to control video games, and usually have one or more push-buttons whose state can also be read by the computer.
A touchpad is a pointing device consisting of specialized surface that can translate the motion and position of a user's fingers to a relative position on screen. Touchpads are a common feature of laptop computers and also used as a substitute for a computer mouse where desk space is scarce. Touchpads can also be found on personal digital assistants (PDAs) and some portable media players, such as the iPod® using a click wheel.